Method of making an optical manifold

ABSTRACT

A three dimensional optical circuit featuring an optical manifold for organizing, guiding and protecting individual optical fibers is shown. One aspect of the present invention is a three dimensional manifold which may be constructed using a rapid prototyping process such as, but not limited to, stereolithography (“SLA”), fused deposition modeling (“FDM”), selective laser sintering (“SLS”), and the like. The manifold has a number of input openings in a first ordered arrangement at one end connected by passageways to a number of output openings in a second ordered arrangement at the opposite end. A plurality of optical fibers may be directed through the passageways of the manifold to produce a three dimensional optical circuit such as a shuffle. Moreover, the optical manifold may be used in conjunction with a number of connections or terminations to form a various optical modules. These modules may be configured for rack mounting within enclosures for electrical components.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of U.S. patent applicationSer. No. 09/927,663 filed on Aug. 10, 2001, which is hereby incorporatedby reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to three dimensionaloptical circuits and, more particularly, to a three dimensional opticalcircuit assembly comprising an optical manifold and a method for makingthe same.

[0004] 2. Background of the Invention

[0005] Optical fiber networks are becoming increasingly common in moderntelecommunications systems, high speed routers, computer systems andother systems for managing large volumes of data. Optical fiber networkstypically comprise a large number of optical fibers which are routedover relatively long distances in order to increase transmission speedsand efficiencies relative to the propagation of conventional electricalsignals. There is often the need to route individual optical fibersbetween various connection points throughout a system creating an“optical circuit”. One of the more common optical circuits in use todayis referred to as an “optical shuffle”. By way of example only, a simpleoptical shuffle may be carried out using eight optical fiber cables eachhaving eight individual optical fibers enclosed therein. In what may bereferred to as a “perfect shuffle”, using the fibers of our examplehere, fiber 1 of each of the eight cables coming in may be routed to asingle first cable going out, and the second fiber of each of the eightcables coming in may be routed to a single second cable going out, andso forth. Referring now to FIG. 1, this particular optical shuffle isrepresented in a simplified schematic in which C_(m) refers to the inputribbon or cable, C_(m)F_(n) refers to the individual fibers F_(n) whichoriginate in cable C_(m), and C_(m)′ is the output ribbon or cablefollowing the optical shuffle. It is to be understood, that althoughthis particular example featured only 64 optical fibers, opticalcircuits often involve a far larger number of fibers which must berouted. Therefore, creating optical shuffles and other optical circuitstructures by hand can be a tedious and highly error prone process. Onecan easily envision the nest of tangled optical fibers occurring incircuits between the input cables and the output cables.

[0006] Several solutions have been proposed for the creation of variousoptical circuits rather than simply trying to route fibers from inputpoints to output points by hand through a large tangle of other fibers.One such solution is the use of semiautomatic machines which weave theindividual fibers into the needed circuit arrangement. This solutionoften requires a significant financial investment in machines which areof little or no use in applications other than the weaving of opticalfibers.

[0007] Another solution to the problem of creating optical circuitsincludes a number of attempts to route optical fibers on a flexiblepolymer substrate. By way of example only, one popular form of thisconstruct is marketed as a Flex Foil®. One such approach to a flexibleoptical circuit solution is set forth and described in U.S. Pat. No.5,204,925 issued to Bonanni et al. This reference describes a solutionin which a flexible polymer substrate such as Mylar® or Kapton® may becoated with a pressure sensitive adhesive (PSA) and have optical fibersmounted thereon. After a number of optical fibers are laid on thesubstrate in the proper arrangement, a protective cover layer, usuallyof the same type of material as the substrate, can be bonded on top ofthe fibers. Of course, the exposed surface of this cover layer maysubsequently be coated with an adhesive itself and additional layers ofoptical fibers and cover materials may be built up in the form of alaminate structure. However, the fiber lay-up process is quite laborintensive and, much like fiber weaving, would require highly specializedequipment to automate. Bonanni et al. further discloses the use offlexible side tabs or thinner strips of substrate material which extendlaterally from the main body where the shuffle has occurred, and permitthe optical fibers to be bent or rotated at, for example, a 90° angle toreorient the fibers from a horizontal position to a vertical position.

[0008] Another approach which incorporates a flexible optical circuit isset forth in U.S. Pat. No. 6,005,991 issued to Knasel. This particularreference discloses a printed circuit board (PCB) assembly that includesan interior portion upon which a flexible optical circuit is mounted.Much like the Bonanni et al. reference, Knasel arranges a plurality ofoptical fibers which are sandwiched between flexible sheets. Theseflexible sheets are commonly formed of Mylar® or the like and hold theoptical fibers in place and are subsequently bonded to other flexiblesheets using pressure sensitive adhesives, as known in the art. In thisreference, space is conserved along the edge of a printed circuit boardby attaching a multifiber connector to the respective first ends of theoptical fibers and using single fiber connectors at the second ends ofthe optical fibers where space is more readily available, such as theless populated interior portion of the printed circuit board.

[0009] It should also be noted that both of these flexible circuitapproaches are generally implemented in the form of large sheets withprerouted fiber networks or printed circuit boards with flexible opticalcircuit portions mounted thereon. In either case, these circuitsnormally have splices at both the input and output ends of the opticalcircuit to facilitate attachment to the input fiber cables and theoutput fiber cables during installation. Splices are normally requiredto overcome the length limitations of the tabs extending from the bodyof the flexible circuit. Additionally, splices may be used to attachspecialized connectors to the input and output ends of the circuit forcoupling to ruggedized cables. The splices at both the input and outputend of the shuffle or optical circuit produce optical signal losseswhich when added across an entire optical network may be significant andunacceptable to the user. Furthermore, both mechanical and fusionsplices commonly require considerable amounts of space because of theneed to mechanically reinforce or strengthen the splice. Additionally,the flexible optical circuit approaches described here generally do notpermit the use of protectively sheathed or “ruggedized” fiber opticribbons leading all the way up to the flexible circuit, nor do theyoffer much protection to the optical fibers within the circuit orshuffle beyond the meager protection provided by a single layer ofpolymer film. Moreover, flexible optical circuit designs do not isolateand protect the individual fibers in that, at crossing points within thecircuit, many of these fibers are in direct contact with each other.

[0010] Therefore, there is a need for three dimensional optical circuitswhich can be created without the expense of weaving machines and whichcan be more readily routed into a number of different shufflearrangements. There is a need for an optical circuit arrangement whichis less labor intensive than building up a multilayer laminate structureof Mylar® film, pressure sensitive adhesive and optical fiber, severalstrands of optical fiber at a time. There is also a need for an opticalcircuit which allows ruggedized ribbons of fiber optic cable to be runup to the circuit and away from the circuit and which provides aruggedized protected environment for the optical fibers during theshuffle itself. There is a need for a three dimensional optical circuithaving fewer fiber splices and reduced optical signal loss.Additionally, there is a need for a three dimensional optical circuitwhich fits into environments with limited surface area (x-y axes) bymore efficiently stacking the shuffle to fully utilize space in avertical direction (z-axis).

SUMMARY OF THE INVENTION

[0011] The three dimensional optical fiber circuit apparatus and methoddescribed herein below will address each of these aforementioned needsand provide a number of additional benefits as well. In one embodiment,the present invention is a rigid, unitary, three dimensional manifoldconstructed using a rapid prototyping process such as, but not limitedto, stereolithography (“SLA”), fused deposition modeling (“FDM”),selective laser sintering (“SLS”), and the like. Note that the termsrapid prototyping and rapid manufacturing are interchangeable in regardto the present invention in that this technology may be utilized notonly for creating prototypes, but actual manufacturing as well.

[0012] Although the equipment for carrying out SLA processes and otherrapid prototyping techniques are relatively expensive machines, thesesystems are general purpose and are readily available. SLA machines andother rapid prototyping machines are readily programmable to createvirtually any three dimensional object which can be designed on acomputer aided design (“CAD”) system. Accordingly, the design of a threedimensional manifold for routing a large number of optical fibers may belaid out in any number of configurations or arrangements limited only tothe capabilities of the CAD system or the imagination of the designer.Moreover, it is possible to program these systems to create passagewaysor channels for routing optical fibers to provide for an appropriatebend radius and thereby minimize optical signal loss, and to isolate andprotect the individual fibers throughout the optical circuit. Further,it is possible to create optical circuits that could not be readilymanufactured using conventional molding or forming techniques.

[0013] The fiber optic manifold, in accordance with the presentinvention, may take any number of possible embodiments, including asolid block having a number of hollow passageways connecting inputpoints and output points or a large plurality of rigid hollow tubeswhich again have a number of input points and output points. By way ofexample only, these input openings may be arranged in a matrix having anequal number of rows and columns. In the case of 8 fiber optic cableseach having 8 fibers, this would require an optical manifold having 64input openings, 64 output openings, and 64 passageways connectingtherebetween. If the input and output ends of the manifold are properlylabeled, it should be relatively easy for a user to determine whichoptical fiber is to be inserted into the appropriate opening and will beexit from the appropriate opening on the opposite end of the manifold.Moreover, since there is only one passageway connecting a particularinput with a particular output there is no need to worry about fibersbecoming entangled within each other or causing confusion for the personguiding them through the manifold.

[0014] In yet another embodiment, the present invention is a process forforming a three dimensional optical circuit including the steps ofproviding a rigid, unitary optical manifold having an input end and anoutput end; arranging a plurality of optical fiber cables leading up tothe input end of the manifold, and arranging a plurality of opticalfiber cables leading away from the output end of the manifold; splittingout the individual fibers of each input cable and guiding each fiber toan individual input opening of the manifold, collecting up theindividual fibers extending from the output openings of the opticalmanifold and gathering them back up into optical cable bundles.Generally, it is possible to merely strip and separate the opticalfibers from the input cables and feed them into the input openings ofthe manifold, passing them through the manifold and then terminating theresulting cable groups at the output side only and have no fiber spliceswithin the shuffle itself. Thus, it is not unreasonable to completelyeliminate optical signal losses incurred by splices within individualoptical circuits, including shuffles. This reduction in optical signallosses could be quite significant if multiplied throughout an entireoptical network.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A more complete understanding of the method and apparatus of thepresent invention may be obtained by reference to the following DetailedDescription when taken in conjunction with the accompanying drawings inwhich like reference numerals refer to like parts and wherein:

[0016]FIG. 1 is a simplified schematic representation of a number cablesand fibers in a perfect 8×8 optical shuffle;

[0017]FIG. 2 is a perspective view of an optical manifold constructed inaccordance with one embodiment of the present invention and featuringcross bracing members to ensure proper spacing and structural rigiditybetween the various rows and columns of the input ends and output endsof the optical manifold;

[0018]FIG. 3 is a perspective view of an optical manifold constructed inaccordance with another embodiment of the present invention featuringstaggered side-by-side inputs and stacked outputs;

[0019]FIG. 4 is a perspective view of the optical manifold in accordancewith the embodiment of FIG. 3 featuring ruggedized cable attachments forreceiving ruggedized cables at one end of the manifold;

[0020]FIG. 5 is a detailed perspective view showing the interiorstructure of a pitch tool aligned with the optical manifold of FIG. 4.

[0021]FIG. 6 is a perspective view of the optical manifold in accordancewith the embodiment of FIG. 3, featuring ruggedized cable attachments atboth the input and output ends of the optical manifold;

[0022]FIG. 7 is a perspective view of an optical manifold in accordancewith yet another embodiment of the present invention, furtherincorporating an input endplate, an output endplate and mountingbrackets.

[0023]FIG. 8 is a bottom view of the optical manifold in accordance withthe embodiment of FIG. 7 and clearly showing the four mounting holeslocated near the corners of the manifold;

[0024]FIG. 9 is a side elevational view of the optical manifold inaccordance with the embodiment of FIG. 7 featuring integral endplates atboth input and output ends;

[0025]FIG. 10 is a detailed perspective view of the optical manifold inaccordance with the embodiment of FIG. 7, featuring the input endplateand the ribbon and fiber numbering system;

[0026]FIG. 11 is a detailed perspective view of the optical manifold inaccordance with the embodiment of FIG. 7, featuring the output endplateand the ribbon and fiber numbering system;

[0027]FIG. 12 is an exploded perspective view an optical manifoldconstructed in accordance with the present invention by stacking aseries of plates having inscribed grooves or channels;

[0028]FIG. 13 is an exploded perspective view an alternative embodimentoptical manifold to that shown in FIG. 12 constructed by stacking aseries of plates having inscribed grooves or channels;

[0029]FIG. 14 is an exploded perspective view an optical manifoldconstructed in accordance with the present invention by stacking aseries of plates having a plurality of fiber guide pieces affixed to asurface to form grooves or channels;

[0030]FIG. 15 is an exploded perspective view an alternative embodimentoptical manifold to that shown in FIG. 14 constructed by stacking aseries of plates having a plurality of fiber guide pieces affixed to asurface to form grooves or channels;

[0031]FIG. 16 is a perspective view of a three dimensional opticalcircuit constructed in accordance with the present invention in whichthe optical manifold has been enclosed within a protective housing andmounted on a plug-in card;

[0032]FIG. 17 is an exploded perspective view of a three dimensionaloptical circuit constructed in accordance with the present invention inwhich a ruggedized optical cable is coupled to a ruggedized cableattachment on the optical manifold;

[0033]FIG. 18 is an exploded perspective view of a three dimensionaloptical circuit constructed in accordance with the present invention andillustrating a shuffling connector with ferrule spring, push-pinconnectors;

[0034]FIG. 19 is an assembled perspective view of the three dimensionoptical circuit shown in FIG. 18 and illustrating a shuffling connectorwith ferrule spring, push-pin connectors; and

[0035]FIG. 20 is a perspective view of a three dimensional opticalcircuit constructed in accordance with the present invention andillustrating an integrated shuffle module with ruggedized fiber inputs,bulkhead connector outputs, and an enclosure suitable for rack mounting.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Referring now to the Figures, and in particular to FIGS. 2-6,there is disclosed a number of embodiments or variations constructed inaccordance with the present invention for providing an optical manifoldwhich may be incorporated into a three dimensional optical circuit suchas a shuffle. As used herein, the term “optical manifold” shall refer toa component of a three dimensional optical circuit which provides anumber of passageways for connecting a set of input openings to a set ofoutput openings and for receiving a plurality of optical fibers in afirst ordered arrangement at the input and outputting the plurality offibers in a second ordered arrangement at the exit. As used in regard tothe openings of an optical manifold, the term “ordered arrangement”refers not to the actual spatial relationship or location of one holerelative to another, but rather to the relationship of an input openingto an output opening.

[0037] By way of example only, an optical manifold for carrying out aperfect shuffle, as described in regard to FIG. 1, may have a firstordered relationship in which the holes of row 1 correspond to fibers1-8 of cable 1, the holes of row 2 correspond to fibers 1-8 of cable 2,and so forth. For this particular shuffle, the holes at the output endof the manifold may have a second ordered relationship in which theholes in row 1 correspond to fiber 1 of cables 1-8, the holes of row 2correspond to fiber 2 of cables 1-8, and so forth. Thus, even though theholes at both ends of the manifold are disposed in an 8×8 array theordered relationship of one hole to another at the input may be quitedifferent from the ordered relationship at the output. In other words,by merely shifting the positions, relative to each other, of at leasttwo fibers passing through an optical manifold, the ordered relationshipof holes at the input end and output end of the manifold must bedifferent.

[0038] Individual optical fibers may be split out of optical cables,guided through the optical manifold, and subsequently interfaced withanother optical fiber, an optical connector, an optical waveguide ornearly any other optical device. It should be further noted that,although each of the examples shown and described herein involve the useof 8 optical cables, each containing 8 optical fibers, for a total of 64individual optical fibers, these optical circuits may involve larger orsmaller numbers of cables and fibers limited only by the imagination ofthe designer, the limitations of the CAD system and the physicallimitations of the stereolithography or other rapid prototypingmachines. Of course, fibers are most commonly bundled in multiples of 4to produce cables having, for example, 8, 12, 16 or 24 fibers each. Itshould also be noted that, although in the examples shown herein theoptical fiber manifolds are constructed of various UV curablephotopolymers, as known in the art, it is also possible to utilize rapidprototyping techniques with various ceramic and metal compounds as well.

[0039] A fairly common optical circuit is that of a perfect shufflewhich is carried out by inputting the individual fibers corresponding torow 1, columns 1-8 and routing them to column 1, rows 1-8, inputting theoptical fibers of row 2, columns 1-8 and routing them to column 2, rows1-8 and so forth. Of course, as will be illustrated in FIGS. 7-11, it isalso possible to also arrange the fibers using an imperfect shufflearrangement in which the fibers of row N are each advanced by N−1 numberof columns from the input to the output end of the manifold. Forexample, in row 1 the fiber corresponding to column 1 at the input willexit at column 1. The fiber corresponding to column 2 at the input willexit at column 2 and so forth, with the fiber at input column 8 exitingat output column 8. In row 2, the fiber at input column 1 will exit atoutput column 2, the fiber at input column 2 will exit at column 3, andso forth with the fiber from input column 8 exiting at output column 1.Again, it is to be understood that these imperfect shuffles may bearranged in any number of ways (e.g., N+1, N−2, or the like), limitedonly by the CAD systems and rapid prototyping machinery used. Onepreferred form of rapid prototyping discussed herein isstereolithography, and although this is not the primary focus of thepresent invention, it is worth noting in some detail how a part isgenerally produced using stereolithography techniques.

[0040] Rapid prototyping is the name given to a host of relatedtechnologies that are commonly used to fabricate three dimensionalphysical objects directly from CAD data sources. These methods aregenerally similar to each other in that they normally create a threedimensional object by building up materials in a layer-wise fashion.Rapid prototyping is also referred to by the name of free formfabrication (“FFF”), layered manufacturing, automated fabrication andother variations of these terms. Stereolithography (“SLA”) is the mostcommonly used rapid prototyping technology. This technique creates threedimensional plastic parts or objects one layer at a time by tracing orrasterizing a laser beam on the surface of a liquid photopolymer. Thisspecialized class of polymer materials quickly solidifies wherever thelaser beam strikes the surface of the liquid. Once one layer of theobject is completely traced, the object is lowered one layer thicknesson a stage into a container filled with photopolymeric material and asecond layer is then traced by the laser right on top of the first. Thephotopolymer is self-adhesive in nature and the layers tend to bond oneto another as they are built up to form a three dimensional object.Following the creation of the three dimensional part, it may be removedfrom the stereolithography apparatus and placed in an ultraviolet (“UV”)post-curing, oven-like apparatus for a more complete cure and addeddimensional stability.

[0041] The technique of selective laser sintering is somewhat similar tostereolithography in that the object is built up one layer at a timeusing a laser tracing a pattern on the surface. However, the polymer orother material is usually in powder form and is heated and fusedtogether by the laser which melts the powder where it strikes under theguidance of a scanning system. Regardless of the rapid prototypingtechnique used, following curing, the resulting three dimensional objectis a single, unitary and integral part and requires little, if any,further machining to produce a finished product. In the case of thevarious embodiments of the present invention, these three dimensionalparts may be referred to as optical manifolds and may be laid out in anynumber of geometries or arrangements but will feature a number of hollowpassageways, tubes or channels for routing individual optical fiberseach from a single input opening to a single output opening of themanifold. The manifold has the additional benefit of being quite rigidand tough enough to protect the optical fibers from variousenvironmental conditions and hazards that may be encountered.

[0042] Referring now to FIG. 2, a perspective view of a stacked eight byeight shuffle manifold 200 is shown. As shown here, the input openings210 and the output openings 220 are arranged in an 8×8 matrix with eachof the columns of the input end and rows of the output end arranged in astacked configuration with support members 230 disposed therebetween.The support members 230 serve to ensure proper spacing of the columnsand rows, and also to provide additional strength and rigidity to thefinished part. When filled with optical fibers, not shown, thisparticular embodiment produces a perfect shuffle in that the individualfibers of row 1 from columns 1-8 are brought together in column 1, rows1-8 of the output end. The fibers of input row 2, columns 1-8 areshuffled to be arranged in column 2, rows 1-8 of the output end and soforth, with the fibers of row 8, columns 1-8 being shuffled into column8, rows 1-8 of the output end of the manifold. It is to be noted thatthe CAD system has been programmed to ensure that none of the individualfibers are forced to experience a bend tighter than the critical bendradius, thereby minimizing optical signal loss and maximizing mechanicallife span for each of the fibers passing through the optical manifold.

[0043] Referring now to FIG. 3, another embodiment of an opticalmanifold 300 constructed in accordance with the present invention isshown. In this particular design, the input openings 310 and the outputopenings 320 of the manifold 300 are again stacked one on top of theother or side-by-side with each other, but the support members disposedtherebetween have been removed. Additionally, at the input end of themanifold 300 columns 1-8 have been staggered side-by-side to provideadditional spacing between each set of input openings 310.

[0044] Referring now to FIG. 4, a manifold 400 constructed in accordancewith the embodiment illustrated in FIG. 3 has been modified by theaddition of a number of ruggedized cable attachments 450, leading to theinput openings 410 of the manifold 400. This manifold 400 is suitablefor receiving up to eight ruggedized fiber optic cables, not shown. Eachof these cables will have a snap-fit member that may be coupled to thecable attachments 450 and then subsequently routed through the opticalmanifold 400. The term “ruggedized” cable generally refers to a type ofoptical cable with a tough polymer exterior which may be furtherreinforced by the use of Kevlar® or other internal tension-bearingmembers. Cables such as these provide the optical fibers with a greatdeal of physical and mechanical protection from harsh externalenvironments.

[0045] Referring now to FIG. 5, a detailed illustration of a multifiberpitch tool 500 is shown. This tool is designed to receive fibers 100having ribbon spacing or ribbon pitch and to split out or spread theindividual fibers of each cable before entering the optical manifold400. The multifiber pitch tool 500 ensures the proper spacing andalignment of the fibers with the input openings of the manifold 410.

[0046] Of course, it is also possible to use this same form ofruggedized cable attachments at the output openings of the manifold togather individual fibers into cable bundles, as shown in FIG. 6.Referring now to FIG. 6, yet another variation of the embodiment shownin FIG. 3 is illustrated. In this particular optical manifold 600,ruggedized cable attachments 650 have been provided at both the input610 and output 620 ends of the manifold 600.

[0047] Referring now to FIGS. 7-11, and in particular to FIG. 7, aperspective view of an imperfect shuffle featuring an input endplate andan output endplate as well as openings for screws or other mountinghardware is shown. Note that in this particular optical manifold 700embodiment the input rows are numbered 1-8 from the bottom to the topand the input columns are numbered 1-8 from left to right. As describedearlier, the individual fibers of this imperfect shuffle are rearrangedin a stepwise fashion. The formula for this shuffle is for row N movethe fiber N−1 columns over. Thus, the fibers in row 1, columns 1-8correlate to output row 1, columns 1-8 without any movement. Theindividual fibers of input row 2, columns 1-8 correspond to output row 2with columns shuffled one step in which the input of column 1corresponds to the output of column 2, the input of column 2 correspondsto the output of column 3 and so forth with the input of column 8corresponding to the output of column 1. Likewise, in row 3, the inputof column 1 corresponds to the output of column 3, the input of column 2corresponds to the output of column 4, and so forth, until the input ofcolumn 8 corresponds to the output of column 2. This progression iscarried on through row 8, in which column 1 corresponds to output column8, input column 2 corresponds to output column 1 and so forth with inputcolumn 8 corresponding to output column 7.

[0048] Referring now to FIG. 8, a bottom view of the optical fibermanifold 700 of FIG. 7 is shown. From this view it is possible toobserve how the 64 individual fiber tubes are arranged to ensure thatthe fibers do not go beneath the minimum bend radius and that, becausethey are enclosed in individual tubes, the individual fibers may be verydensely overlapped without worry of entanglement. Additionally, thisfigure shows the input endplate 705, the output endplate 715 and theholes 730 extending through the entire depth of the object for screws orother mounting hardware. It should be noted that the manifold 700 may bemounted in any number of systems or configurations, as well as attachedto a removable card, much like a printed circuit board, as known in theart. Additionally, although this manifold 700 is shown without any sortof connectors or terminations at the input 710 or output 720 end, it isto be understood that multifiber attachments or individual fiberconnections or terminations may be used at the input and output ends ofthe manifold 700, much like those illustrated in FIGS. 4 and 6.

[0049] Referring now to FIG. 9, a side elevational view of the manifoldof FIG. 7 is shown. This figure best illustrates the stacked verticalarrangement of each of the layers of individual tubes, channels orpassageways that make up the manifold 700. As a result of the rapidprototyping techniques used, it is possible to achieve an incrediblycompact and efficient design without fear of fiber entanglement orsignificant optical signal loss. Rapid prototyping also allows adjacentpassageways or tubes to share a common sidewall. Accordingly, a manifold700 produced in accordance with the present invention will be far morecompact than a collection of preformed tubes that have been broughttogether to form a manifold.

[0050] Referring now to FIG. 10, an enlarged perspective view of themanifold of FIG. 7 is shown. Here, the input end 710 of the manifold 700is clearly illustrated indicating markings for a user to identify theribbon or cable numbers from 1 to 8 and the individual fibers that makeup those cables, again from 1 to 8 at the input end. Of course, the rowsand columns of the manifold may be labeled or color-coded in almost anymanner which facilitates proper identification.

[0051] Referring now to FIG. 11, another enlarged perspective drawing ofthe manifold embodiment shown in FIG. 7. This particular figure bestillustrates the output end 720 of the manifold 700 again featuring anumbering guide for users illustrating the ribbon or cable numbers from8 to 1 and the fiber numbers ranging from 1 to 8. It is believed thatone of the unique benefits of the present invention is that itfacilitates a shuffle of any number of mathematical arrangements in anearly error proof manner by merely feeding the properly numbered orcolor-coded fiber of each input cable and then collecting the fibersinto the appropriate output cables at the opposite end of the manifold.In short, as long as the appropriate fibers are fed into the properinput holes, they must emerge at the appropriate output holes of themanifold and be collected into the appropriate multifiber cables orbundles.

[0052] Referring now to FIG. 12, another alternative embodimentconstructed in accordance with the present invention is shown. The bodyof an optical manifold 800 may be constructed by building up a series ofstacked plates 810. Each of these plates 810 will have a number ofgrooves or channels 820 extending completely across its length from theinput end 830 to the output end 840 of the plate 810. As the plates 810are indexed to align the edges and stacked to form an optical manifold800, the channels 820 in each plate 810 act as passageways connectinginput openings at one end of the manifold 800 with output openings atthe opposite end of the manifold. Of course, these plates may bemanufactured by a number of different techniques including, but notlimited to, milling channels into a solid plate, molding the plate withchannels on a surface, or building the plate up in a layer additiveprocess such as those described hereinabove.

[0053] Referring now to FIG. 13, an alternative embodiment of theoptical manifold set forth and described in regard to FIG. 12 is shown.As in the embodiment of FIG. 12, the body of an optical manifold 900 maybe constructed by building up a series of stacked plates 910 in whicheach of these plates has a number of grooves or channels 920 extendingcompletely across its length from the input end 930 to the output end940 of the plate 910. However, in this particular embodiment, thechannels or grooves 920 are arranged on each plate to avoid anyintersections. This may be done to prevent fibers from coming in directcontact with each other or being possibly misdirected into the wrongchannel 920 while passing from the input end 930 to the output end 940of the manifold 900. As shown here, a manifold constructed in thismanner will require at least twice the number of grooved plates 910 tofacilitate the same optical circuit constructed from plates which allowthe channels to intersect and the fibers to touch. This also results ina stacked plate manifold which is much taller or larger in thez-direction than the embodiment depicted in FIG. 12.

[0054] Referring now to FIGS. 14 and 15, a manufacturing variation ofthe stacked plate manifolds shown in FIGS. 12 and 13, respectively, isshown. The manifold embodiments 800′, 900′ as shown in FIGS. 14 and 15are again created by stacking plates 810′, 910′ one on top of anotherand indexing them to form a manifold. However, the embodiments of FIGS.14 and 15 do not have channels or grooves 820′, 920′ which are milled,cut or molded into the plates, but rather a large number of individualguide pieces 850′, 950′ which are glued, affixed or attached in somemanner to a particular plate 810′, 910′ to create a pattern thereon. Asone skilled in the art will recognize, the labor or manufacturing stepsrequired to produce a large number of guide pieces, attach them to theirrespective plates, and then stack the plates one on top of another toform a manifold would be considerable, particularly in comparison toplates formed by milling, injection molding, or other productiontechniques. FIGS. 14 and 15 are provided to show yet another approach tocreating a stacked plate manifold as depicted in FIGS. 12 and 13.

[0055] Referring now to FIG. 16, a perspective view of an opticalmanifold that has been enclosed within a protective housing 1010 andmounted on a plug-in card 1020 is shown. This embodiment may also bereferred to as a plug-in optical shuffle module 1000. As shown here,ruggedized and ribbonized optical cables 50 are directed to multifiberattachments 1050 and the unterminated fiber ends are inputted to anoptical shuffle in accordance with the present invention. The opticalmanifold is enclosed within a protective housing 1010 of molded polymer,formed sheet metal embedded in epoxy or the like. Following the shuffle,the individual fibers are again gathered into ribbonized bundles 60 anddirected to blind-mate, plug-in or other optical card connectors 1060.These connectors 1060 serve as terminations that are adapted to allowfiber connections at the edge of the plug-in card 1020 and allow theoptical shuffle to be implemented in a fully modular quick-connectdesign.

[0056] Referring now to FIG. 17, a three dimensional optical circuit1200 with an exploded detail view of a single ruggedized optical fibercable 50 attached thereto is shown. The three dimensional opticalcircuit features an optical manifold 400 similar to that set forth anddescribed in regard to FIG. 4. This manifold features eight ruggedizedcable attachments 450 at the input end, which are designed to receive asnap fit, crimp barb 1230 to facilitate the transfer of mechanical loadsand stresses from the ruggedized exterior of the optical cable 50through the crimp barb 1230 and into the body of the optical manifold400 itself. In short, one of the unique and surprising features of anoptical circuit utilizing the optical manifold of the present inventionis that mechanical loads or stresses may actually be transferred to andcarried by the unitary body of the manifold itself. This is quitedifferent from flexible substrate or woven fiber approaches in that themanifold itself can provide stress relief to the fibers which arepassing therethrough. It is the inventors' belief that the prior artdoes not show any sort of apparatus which could both shuffle or organizeoptical fibers into a circuit while also carrying a mechanical load orproviding stress relief to the fibers themselves.

[0057] As shown here, a ruggedized cable 50 containing a number ofoptical fibers 100 is passed through a manifold 400 by first cuttingback the ruggedized exterior portion of the cable 50; passing theexposed fibers 100 through a strain relief boot 1210, a crimp ring 1220and a crimp barb 1230; crimping the crimp ring 1220 to the load bearingruggedized exterior of the cable 50; fitting the crimp ring 1220 withinthe crimp barb 1230 to transfer mechanical stresses from the ruggedizedcable 50 to the barb 1230; and finally connecting the barb 1230 to theruggedized attachment 450 of the manifold 400 to transfer stresses fromthe cable 50 to the crimp ring 1220 to the crimp barb 1230 to themanifold itself 400. As the optical fibers 100 of the ruggedized cable50 are passed through the ruggedized attachment 450, they may be spreadusing a pitch tool or the like to ensure proper alignment with themanifold 400. Finally, the optical fibers 100 are guided and insertedinto the appropriate input openings 410 of the optical manifold 400 tocreate a three dimensional optical circuit.

[0058] Referring now to FIG. 18, a three dimensional optical circuitconstructed for use as a shuffling connector 1400 with ferrule spring,push-pin connectors 1410 is shown. As shown here, a particularly smalloptical shuffle 1450 may be used to arrange optical fibers 100 into athree dimensional circuit and output the fibers to shuffle adapters 1460which gather individual fibers 100 back together into bundles orribbonized form. The ribbonized fiber bundles 60 may then be terminatedin a ferrule spring, push-pin type connector 1410 for use with a blindmate card connector 1420, as shown. It is possible to envision aparticularly small shuffling connector 1400 such as this fitting withinvarious environments including enclosures for electronics as a sort ofoptical plug-in card or module. This small, highly efficient modulardesign is quite different from the significantly greater amounts ofsurface space required to create optical circuits including shufflesusing prior art flexible substrate techniques and optical fiber splicesto attach the appropriate connectors.

[0059] As best seen in FIG. 19, an assembled shuffling connector 1400may be quite compact in design. This entire modular component may beless than 2.0 inches in both length and width, and less than 1.0 inch inheight. For comparison purposes, a flexible substrate optical circuitconfigured to carry out a similar function, may require 12.0 inches ormore in both the length and width directions, and while being thinner inthe z-direction, it is difficult to allow for such large surface areaswithin the densely packed environment of an electronic enclosure.

[0060] Referring now to FIG. 20, a perspective view of a threedimensional optical circuit illustrating an integrated shuffle module1500 having ruggedized fiber inputs 1510, bulkhead connector outputs1520, and a housing 1550 suitable for rack mounting is shown. Themodular design shown here, features a durable housing 1550 suitable forrack mounting within an electronic enclosure. This particular threedimensional optical circuit features an optical manifold 700 of theembodiment shown and described in regard to FIGS. 7-11. It furtherincludes fiber routing features or fins 1530 for guiding the opticalfibers through a safe bend radius within the housing 1550 and toward theoptical terminations and bulkhead connectors 1520 provided at the outputof the module 1500. It should also be noted that at the input of thismodule 1500 there are provided ruggedized cable attachments 1510 adaptedto receive fibers from ruggedized cables 50, of nearly any length, andfor efficiently transmitting mechanical loads and stresses from theruggedized cables 50 into the body of the housing itself to againprovide stress relief for the optical fibers. Although this modulardesign features one particular form of optical manifold, one skilled inthe art will appreciate that virtually any optical manifold, andparticularly those created in accordance with the unitary body, rapidprototyping optical manifold embodiments of the present invention.

[0061] Although preferred embodiments of the invention have beendescribed in the examples and foregoing description, it will beunderstood that the invention is not limited to the embodimentsdisclosed, but is capable of numerous rearrangements and modificationsof the parts and elements without departing from the spirit of theinvention, as defined in the following claims. Therefore, the spirit andthe scope of the appended claims should not be limited to thedescription of the preferred embodiments contained herein.

What is claimed is:
 1. A method of making an optical manifold,comprising the steps of: (a) creating a CAD data source representativeof the optical manifold; and (b) creating the optical manifold by arapid prototyping process using the CAD data source.
 2. A method ofmaking an optical manifold, comprising the steps of: (a) designing theoptical manifold using a CAD system programmed to ensure that noindividual fiber positioned within the manifold is forced to experiencea bend tighter than a critical bend radius; and (b) creating the opticalmanifold by a rapid prototyping process using data from the CAD system.3. A method of making an optical manifold, comprising the steps of: (a)designing the optical manifold using a CAD system so that adjacentpassageways for optical fibers share a common sidewall; and (b) creatingthe optical manifold by a rapid prototyping process using data from theCAD system.